When I am sewing/quilting at home I wear my "quilting outfit" (according to the kids!). This is a very thin, lightweight top (cotton/lycra mix) which is very loose and baggy, over very lightweight leggings with a very loose elasticated waist. Thanks to Primark, this outfit is cheap as chips, and I don't feel guilty if it falls apart!.
It lets me move around and bend properly if I have to use the floor for laying stuff out/cutting. I also wear a pair of cotton "slippers" which I made from a pattern free on the internet. They are lightweight but protect my feet from the worst of the pins! I have a pair of baggy jogging bottoms (sweat pants) that go over the top of the leggings if I am cold in the nether regions, and likewise an old baggy fleece top if I am chilly further up.